E4329_QuickGuide.pdf

Quick Guide to Precision Measuring Instruments
E4329

2

3 Quick Guide to Precision Measuring Instruments
CONTENTS
Meaning of Symbols 4
Conformance to CE Marking 5
Micrometers 6
Micrometer Heads 10
Internal Micrometers 14
Calipers 16
Height Gages 18
Dial Indicators/Dial Test Indicators 20
Gauge Blocks 24
Laser Scan Micrometers and Laser Indicators 26
Linear Gages 28
Linear Scales 30
Profile Projectors 32
Microscopes 34
Vision Measuring Machines 36
Surftest (Surface Roughness Testers) 38
Contracer (Contour Measuring Instruments) 40
Roundtest (Roundness Measuring Instruments) 42
Hardness Testing Machines 44
Vibration Measuring Instruments 46
Seismic Observation Equipment 48
Coordinate Measuring Machines 50

4
Meaning of Symbols
Mitutoyo's technology has realized the absolute position method (absolute method). With this method, you do not have to reset the system
to zero after turning it off and then turning it on. The position information recorded on the scale is read every time. The following three types
of absolute encoders are available: electrostatic capacitance model, electromagnetic induction model and model combining the electrostatic
capacitance and optical methods. These encoders are widely used in a variety of measuring instruments as the length measuring system that can
generate highly reliable measurement data.
Advantages:
1. No count error occurs even if you move the slider or spindle extremely rapidly.
2. You do not have to reset the system to zero when turning on the system after turning it off*1
.
3. As this type of encoder can drive with less power than the incremental encoder, the battery life is prolonged to about 3.5 years (continuous
operation of 20,000 hours)*2
under normal use.
*1: Unless the battery is removed.
*2: In the case of the ABSOLUTE Digimatic caliper.
• The electromagnetic-induction-type absolute encoder is patent-protected in Japan, the United States, the United Kingdom, Germany, France, India and China.
• The absolute encoder combining the electrostatic capacitance and optical methods is patent-protected in Japan, the United States, the United Kingdom, Germany,
Switzerland, Sweden and China.
These are codes that indicate the degree of protection provided (by an enclosure) for the electrical function of a product against the ingress of foreign bodies, dust and water as defined
in IEC standards (IEC 60529) and JIS C 0920. Due to ongoing development of new length measuring systems, Mitutoyo builds metrology products qualified to protection codes IP65, IP66
and IP67, which signifies that these products may be used in hostile environments. [IEC: International Electrotechnical Commission]
IP65, IP66 and IP67 protection level ratings for applicable Mitutoyo products have been independently confirmed by the German accreditation organization, TÜV Rheinland.
First
characteristic
numeral
Degrees of protection against solid foreign objects
Brief description Definition
0 Unprotected —
1
Protected against solid
foreign objects of
Sø50mm and greater
A Sø50mm object probe
shall not
fully penetrate enclosure1)
2
Protected against
solid foreign objects
of Sø12,5mm and
greater
A Sø12,5mm object probe
shall not
fully penetrate enclosure1)
3
foreign objects of
Sø2,5mm and greater
shall not
penetrate enclosure1)
4
foreign objects of
Sø1,0mm and greater
shall not
penetrate enclosure1)
5 Protected against dust
Ingress of dust is not
totally prevented, but
dust that does penetrate
must not interfere with
satisfactory operation of
the apparatus or impair
safety
6 Dust-proof No ingress of dust allowed
1)The full diameter of the object probe shall not pass through an opening in the
enclosure.
Second
characteristic
numeral
Degrees of protection against water
Brief description Definition
0 Unprotected —
1
Protected against
vertically falling water
drops
Vertically falling drops shall have no harmful effects
2
Protected against
vertically falling water
drops when enclosure
title up to 15°
Vertically falling drops shall have no harmful effects when the
enclosure is tilted at any angle up to 15 degrees either side of
the vertical
3
Protected against
spraying water
Water sprayed at an angle up to 60° either side of the vertical
shall have no harmful effects
4
Protected against
splashing water
Water splashed against the enclosure from any direction shall
have no harmful effects
5
Protected against
water jets
Water projected in moderately powerful jets against the
enclosure from any direction shall have no harmful effects
6
Protected against
powerful water jets
Water projected in powerful jets against the enclosure from any
direction shall have no harmful effects
7
Protected against the
effects of temporary
immersion in water
Ingress of water in quantities causing harmful effects shall not
be possible when the enclosure is temporarily immersed in water
under standardized conditions of pressure and time
8
Protected against the
effects of continuous
immersion in water
Ingress of water in quantities causing harmful effects shall not be
possible when the enclosure is continuously immersed in water
under conditions which shall be agreed between manufacturer
and user but which are more severe than for IPX7
Note: For details of the test conditions used in evaluating each degree of protection, please refer to the original standard.
IP
Independent Confirmation of Compliance
IP Codes
ABSOLUTE Linear Encoder

Conformance to CE Marking
In order to improve safety, each plant has programs to comply
with the Machinery Directives, the EMC Directives, and the Low
Voltage Directives. Compliance to CE marking is also satisfactory.
CE stands for Conformité Européenne. CE marking indicates
that a product complies with the essential requirements of the
relevant European health, safety and environmental protection
legislation.
The RoHS directive* is a set of European regulations for the use of certain hazardous substances. Since July 1, 2006, selling specified
electronic equipment containing more than the regulation amount of the specified six substances (lead, cadmium, mercury, hexavalent
chromium, polybrominated biphenyl (PBB), and polybrominated diphenyl ether (PBDE)) is prohibited in Europe.
The scope of the RoHS directive is based on the 10 categories in the WEEE** directive. However, medical devices and monitoring and
control instruments are excluded.
Mitutoyo is actively promoting environmental protection by developing RoHS-compliant products.
* RoHS directive: Directive of the European Parliament and of the Council on the restriction of the use of certain hazardous substances in electrical
and electronic equipment
** WEEE directive: Waste Electrical and Electronic Equipment Directive
EC Directives Related to Mitutoyo Products
Directive Scope
Machinery directive Equipment that has parts moved by an actuator such as a motor and might cause human injury
EMC (electromagnetic compatibility)
directive
Apparatus (devices) that is likely to generate, or be affected by, electromagnetic disturbance
Low voltage directive
Apparatus (devices) that operate at the voltages below, and might cause electrical shock, electrocution, heat,
or radiation
AC voltage: 50 to 1,000 V DC voltage: 75 to 1,500 V
RoHS Directive Compliance

6
Micrometers
Frame
Anvil
Measuring faces
Spindle
Outer sleeve
Inner sleeve
Adjusting nut
Ratchet stop
Heat insulator
Spindle lock
Index line on sleeve
Thimble
Heat insulator
Measuring faces
Frame
Anvil
Thimble
Spindle lock
Outer sleeve
Output connector (for data output type only)
Ratchet stop
ZERO (INC)/ABS set key
Origin key
HOLD key
Standard Outside Micrometer
■ Nomenclature
Digimatic Outside Micrometer
■ Special Purpose Micrometer Applications
Spindle
Blade micrometer Inside micrometer, caliper type Spline micrometer Tube micrometer
Point micrometer Screw thread micrometer Disc type outside micrometer V-anvil micrometer
For diameter inside narrow
groove measurement
For small internal diameter, and
groove width measurement
For splined shaft diameter
measurement
For pipe thickness measurement
For root diameter measurement For effective thread diameter
measurement
For root tangent measurement on
spur gears and helical gears
For measurement of
3- or 5-ﬂute cutting tools

■ Detailed Shape of Measuring Faces
■ How to Read the Scale
Micrometer with standard scale (graduation: 0.01mm)
The scale can be read directly to 0.01mm, as shown above, but may
also be estimated to 0.001mm when the lines are nearly coincident
because the line thickness is 1/5 of the spacing between them.
Micrometer with vernier scale (graduation: 0.001mm)
The vernier scale provided above the sleeve index line enables direct
readings to be made to within 0.001mm.
Micrometer with digital display (resolution: 0.001mm)
Sleeve reading 6. mm
Thimble reading .21mm
Reading from the vernier scale marking
and thimble graduation line .003mm
Micrometer reading 6.213mm
Audible in
operation
One-handed
operation
Remarks
Ratchet stop
Yes Unsuitable
Audible clicking operation causes
micro-shocks
Friction thimble
(F type)
No Suitable
Smooth operation without shock or
sound
Ratchet thimble
(T type)
Yes Suitable
Audible operation provides confirma-
tion of constant measuring force
Ratchet thimble
Yes Suitable
Audible operation provides confirma-
tion of constant measuring force
■ Constant-force Devices
■ Potential Reading Error Due to
Parallax
When a scale and its index line do not lie in the same plane it is possible
to make a reading error due to parallax, as shown below. The viewing
directions (a) and (c) will produce this error, whereas the correct reading
is that seen from direction (b).
■ Difference in Thermal Expansion
between Micrometer and Standard
Bar
The graphs above show the change in size of a standard length bar
when held in the hand at palm temperatures of 21˚C, 27˚C and 31˚C.
■ Standard Bar Expansion with
Change of Temperature (for 200mm bar initially at 20˚C)
These drawings above are used for explaration and they are not to scale
Sleeve reading 7. mm
Thimble reading + .37mm
Micrometer reading 7.37mm
(b)
(c)
(a)
Thimble
Sleeve
Sleeve index line Sleeve index line
Thimble graduation line Thimble graduation line
Approx. +1µm Approx. +2µm
125
-3
-2
-1
0
+1
+2
+3
225 325
0˚C
20˚C
10˚C
425 525
Difference
in
expansion
(µm)
Nominal length (mm)
31˚C
27˚C
21˚C
Lapse of time (minutes)
Thermal
expansion
(µm)
10
9
8
7
6
5
4
3
2
1
0
20
15
10
5
0
Third decimal place
Second decimal place
First decimal place
Millimetres
Tens of mm
0 2 9 9
mm
6
4
5
0
45
2
0
0.01
+
2.994mm
.004mm
.09 mm
.9 mm
2. mm
00. mm
Third decimal place on vernier scale ( 0.001 mm units)
Vernier reading 0.004mm
Counter reading
Index line
ø6.35
ø6.3
30’
ø8
30’
ø7.95
Carbide tip
spindle
spindle

8
Supporting point Supported at the bottom and center Supported only at the center
Attitude
Maximum
measuring
length (mm)
325 0 −5.5
425 0 −2.5
525 0 −5.5
625 0 −11.0
725 0 −9.5
825 0 −18.0
925 0 −22.5
1025 0 −26.0
■ Measurement Error Depending on
Attitude and Supporting Point (Unit: µm)
Supporting point Supported at the center in a lateral
orientation.
Supported by hand downward.
Attitude
Maximum
measuring
length (mm)
325 +1.5 −4.5
425 +2.0 −10.5
525 −4.5 −10.0
625 0 −5.5
725 −9.5 −19.0
825 −5.0 −35.0
925 −14.0 −27.0
1025 −5.0 −40.0
■ Abbe’s Principle
Abbe’s principle states that “maximum accuracy is obtained when the
scale and the measurement axes are common”.
This is because any variation in the relative angle (q) of the moving
measuring jaw on an instrument, such as a caliper jaw micrometer
causes displacement that is not measured on
the instrument’s scale and this is an Abbe error
(e= −L in the diagram). Spindle straightness error,
play in the spindle guide or variation of
measuring force can all cause q to vary
and the error increases with R.
■ Hertz's Formulae
Hertz’s formulae give the apparent reduction in diameter of spheres and
cylinders due to elastic compression when measured between plane
surfaces. These formulae are useful for determining the deformation of
a workpiece caused by the measuring force in point and line contact
situations.
■ Effective Diameter of Thread
Measurement
●Three-wire Method of Thread Measurement. The effective diameter
of a thread can be measured by using three wires contacting
the thread as shown in figure below. Effective diameter E can be
calculated by using formula (1) or (2).
For metric or unified screw threads (60˚ thread angle)
E=M−3d+0.866025P .......(1)
For Whitworth screw threads (55˚ thread angle)
E=M−3.16568d+0.960491P .......(2)
Where, P: Screw thread pitch (A pitch in
inches is converted to its metric
equivalent for unified screw threads.)
d: Mean diameter of the three wires
E: Effective diameter of the thread
M: Measurement over the three wires
Micrometers
Anvil
Spindle
Odd-fluted tap Wire
Screw thread type Best wire size
Metric screw thread (60°) 0.577P
Whitworth screw thread (55°) 0.564P
Single-wire Method of Thread Measurement. An Odd-fluted tap can be
measured using a V-anvil micrometer and a single wire in contact with
the thread flanks as shown. This method uses two measurements and
a calculation to obtain an equivalent value for M as was obtained by
direct measurement in the `three-wire’ method.
Where, M1: Maximum micrometer reading over the single wire (at
cutting edge)
D: Maximum diameter of tap (at cutting edge)
For a three-flute tap: M = 3M1 − 2D
Or for a five-flute tap: M = 2.2360M1 − 1.23606D
Then, the effective diameter E can be calculated by substituting this M
in formula (1) or (2)
Assuming that the material is steel and units are as follows:
Modulus of elasticity: E=196 GPa
Amount of deformation: δ (µm)
Diameter of sphere or cylinder: D (mm)
Length of cylinder: L (mm)
Measuring force: P (N)
a) Apparent reduction in diameter of sphere
δ1 =0.82
3
√P2
/D
b) Apparent reduction in diameter of cylinder
δ2 =0.094·P/L
3
√1/D
L ε
R
θ
P
SøD
2
2
P
2
2
L
øD
(a)
Sphere between
two planes
(b)
Cylinder between
two planes
Since the measurement value is changed by the supporting point and
maximum measuring length, it is recommended to use the instrument
by performing zero-setting with the same orientation as it will be used
in practice.

■ Hooke's Law
Hooke’s law states that strain in an elastic material is proportional to the
stress causing that strain, providing the strain remains within the elastic
limit for that material.
■ Testing Parallelism of Micrometer
Measuring Faces
Parallelism can be estimated using an optical parallel held between the
faces. Firstly, wring the parallel to the anvil measuring face. Then close
the spindle on the parallel using normal measuring force and count
the number of red interference fringes seen on the measuring face of
the spindle in white light. Each fringe represents a half wavelength
difference in height (0.32μm for red fringes).
In the above figure a parallelism of approximately 1µm is obtained from
0.32µm x 3=0.96µm.
■ Testing Flatness of Micrometer
Measuring Faces
Flatness can be estimated using an optical flat (or parallel) held against
a face. Count the number of red interference fringes seen on the
measuring face in white light. Each fringe represents a half wavelength
difference in height (0.32μm for red).
Measuring face is curved by
approximately 1.3μm. (0.32μm x 4
paired red fringes.)
Measuring face is concave (or
convex) approximately 0.6μm deep.
(0.32μm x 2 continuous fringes)
Fringes on the spindle side
Optical parallel reading direction on the spindle side
Optical parallel
Anvil
Optical ﬂat Optical ﬂat
Anvil
Interference fringe
reading direction

10
Key Factors in Selection
Key factors in selecting a micrometer head are the measuring range, spindle face, stem, graduations, thimble diameter, etc.
■ Stem
●If a micrometer head is used as a stop it is desirable to use a head
fitted with a spindle lock so that the setting will not change even
under repeated shock loading.
●The stem used to mount a micrometer head is classified as a "plain
type" or "clamp nut type" as illustrated above. The stem diameter
is manufactured to a nominal Metric or Imperial size with an h6
tolerance.
●The clamp nut stem allows fast and secure clamping of the
micrometer head. The plain stem has the advantage of wider
application and slight positional adjustment in the axial direction on
final installation, although it does requires a split-fixture clamping
arrangement or adhesive fixing.
●General-purpose mounting fixtures are available as optional
accessories.
Plain stem Stem with clamp nut
●A flat measuring face is often specified where a micrometer head is
used in measurement applications.
●When a micrometer head is used as a feed device, a spherical face
can minimize errors due to misalignment (Figure A). Alternatively, a
flat face on the spindle can bear against a sphere, such as a carbide
ball (Figure B).
●A non-rotating spindle type micrometer head or one fitted with an
anti-rotation device on the spindle (Figure C) can be used if a twisting
action on the workpiece must be avoided.
●If a micrometer head is used as a stop then a flat face both on the
spindle and the face it contacts provides durability.
Flat face Spherical face Anti-rotation device
Micrometer Heads
■ Measuring Face
■ Non-Rotating Spindle
A non-rotating spindle type head does not exert a twisting action on a
workpiece, which may be an important factor in some applications.
■ Spindle Thread Pitch
●The standard type head has 0.5mm pitch.
●1mm-pitch type: quicker to set than standard type and avoids
the possibility of a 0.5mm reading error. Excellent load-bearing
characteristics due to larger screw thread.
●0.25mm or 0.1mm-pitch type
This type is the best for fine-feed or fine-positioning applications.
■ Constant-force Device
●A micrometer head fitted with a constant-force device (ratchet or
friction thimble) is recommended for measurement applications.
●If using a micrometer head as stop, or where saving space is a
priority, a head without a ratchet is probably the best choice.
■ Spindle Lock
Figure A Figure B
Figure C
Micrometer head with
constant-force device
Micrometer head without
constant-force device (no ratchet)

●The diameter of a thimble greatly affects its usability and the
"fineness" of positioning. A small-diameter thimble allows quick
positioning whereas a large-diameter thimble allows fine positioning
and easy reading of the graduations. Some models combine the
advantages of both features by mounting a coarse-feed thimble
(speeder) on the large-diameter thimble.
Normal
graduation style
Reverse
graduation style
Bidirectional
graduation style
■ Measuring Range (Stroke)
●When choosing a measuring range for a micrometer head, allow
an adequate margin in consideration of the expected measurement
stroke. Six stroke ranges, 5 to 50mm, are available for standard
micrometer heads.
●Even if an expected stroke is small, such as 2mm to 3mm, it will be
cost effective to choose a 25mm-stroke model as long as there is
enough space for installation.
●If a long stroke of over 50mm is required, the concurrent use of a
gauge block can extend the effective measurement range. (Figure D)
■ Ultra-fine Feed Applications
●Dedicated micrometer heads are available for manipulator
applications, etc., which require ultra-fine feed or adjustment of
spindle.
■ Thimble Diameter
■ Graduation Styles
●Care is needed when taking a reading from a mechanical micrometer
head, especially if the user is unfamiliar with the model.
●The "normal graduation" style, identical to that of an outside
micrometer, is the standard. For this style the reading increases as the
spindle retracts into the body.
●On the contrary, in the “reverse graduation” style the reading
increases as the spindle advances out of the body.
●The "bidirectional graduation" style is intended to facilitate
measurement in either direction by using black numerals for normal,
and red numerals for reverse, operation.
●Micrometer heads with a mechanical or electronic digital display,
which allow direct reading of a measurement value, are also
available. These types are free from misreading errors. A further
advantage is that the electronic digital display type can enable
computer-based storage and statistical processing of measurement
data.
Gauge block
Head’s stroke
Obtained stroke
Figure D

12
Micrometer Heads
Mounting
method
Points to keep
in mind
(1) Clamp nut (2) Split-body clamp (3) Setscrew clamp
Stem diameter ø9.5 ø10 ø12 ø18 ø9.5 ø10 ø12 ø18 ø9.5 ø10 ø12 ø18
Mounting hole
Fitting tolerance
G7
+0.006 to +0.024
G7
+0.005 to +0.020
G7
+0.005 to +0.020
G7
+0.006 to +0.024
H5
0 to +0.006
H5
0 to +0.008
Precautions
Care should be taken to make Face A square to the mount-
ing hole.
The stem can be clamped without any problem at square-
ness within 0.16/6.5.
Remove burrs generated on the wall of the mounting hole
by the slitting operation.
M3x0.5 or M4x0.7 is an appropriate size for the setscrew.
Use a brass plug under setscrew (if thickness of fixture al-
lows) to avoid damaging stem.
■ Guidelines for Self-made Fixtures
A micrometer head should be mounted by the stem in an accurately machined hole using a clamping method that does not exert excessive force on
the stem. There are three common mounting methods as shown below. Method 3 is not recommended. Adopt methods (1) or (2) wherever possible.
■ Maximum Loading Capacity on Micrometer Heads
The maximum loading capacity of a micrometer head depends mainly on the method of mounting and whether the loading is static or dynamic (used
as a stop, for example). Therefore the maximum loading capacity of each model cannot be definitively specified. The loading limits recommended by
Mitutoyo (at less than 100,000 revolutions if used for measuring within the guaranteed accuracy range) and the results of static load tests using a
small micrometer head are given below.
Test method
Micrometer heads were set up as shown and the
force at which the head was damaged or pushed
out of the fixture when a static load was applied, in
direction P, was measured. (In the tests no account
was taken of the guaranteed accuracy range.)
* These load values should only be used as an approximate guide.
1. Recommended maximum loading limit
(Unit: mm)
Maximum loading limit
Standard type (spindle pitch: 0.5mm) Up to approx. 4kgf *
High-functionality type
Spindle pitch: 0.1mm/0.25mm Up to approx. 2kgf
Spindle pitch: 0.5mm Up to approx. 4kgf
Spindle pitch: 1.0mm Up to approx. 6kgf
Non-rotating spindle Up to approx. 2kgf
MHF micro-fine feed type (with a differential mechanism) Up to approx. 2kgf
Mounting method Damaging/dislodging load*
(1) Clamp nut Damage to the main unit will occur at 8.63 to 9.8kN (880 to 1000kgf).
(2) Split-body clamp The main unit will be pushed out of the fixture at 0.69 to 0.98kN (70 to
100kgf).
(3) Setscrew clamp Damage to the setscrew will occur at 0.69 to 1.08kN (70 to 110kgf).
(3) Setscrew clamp
(2) Split-body clamp
(1) Clamp nut
2. Static load test for micrometer heads (using MHS for this test)
* Up to approx. 2kgf only for MHT
Split-body clamp
P
Setscrew
P
P
Clamp nut
Face A

■ Custom-built Products (Product Example Introductions)
Micrometer heads have applications in many fields of science and industry and Mitutoyo offers a wide range of standard models to meet customers’
needs. However, in those cases where the standard product is not suitable Mitutoyo can custom build a head incorporating features better suited to
your special application. Please feel free to contact Mitutoyo about the possibilities - even if only one custom-manufactured piece is required.
1. Spindle-end types
2. Stem types
A custom stem can be manufactured to suit the mounting fixture.
3. Scale graduation schemes
Various barrel and thimble scale graduation schemes, such as reverse and vertical, are available.
Please consult Mitutoyo for ordering a custom scheme not shown here.
9. All-stainless construction
All components of a head can be
manufactured in stainless steel.
10. Simple packaging
Large-quantity orders of micrometer heads
can be delivered in simple packaging for OEM
purposes.
7. Spindle-thread pitch
Pitches of 1mm for fast-feed applications or 0.25mm for fine-feed can
be supplied as alternatives to the standard 0.5mm. Inch pitches are also
supported. Please consult Mitutoyo for details.
8. Lubricant for spindle threads
Lubrication arrangements can be specified by
the customer.
4. Logo engraving
A specific logo can be engraved as required.
5. Motor Coupling
Couplings for providing motor
drive to a head can be designed.
● Standard
● Plain
● Standard ● Reverse ● Vertical
● Reverse vertical
● Ratchet ● Setscrew ● Hex-socket head screw
● Offset zero ● Graduations only
● Clamp nut ● Threaded ● Flanged
● Spherical ● Pointed ● Spline ● Tapped ● Flanged ● Blade (for non-rotating spindle
type only)
● Long spindle type is also available. Please consult Mitutoyo.
6. Thimble mounting
Thimble mounting methods including a ratchet, setscrew, and hex-socket
head screw types are available.

14
Type of
feature
Workpiece profile (example) Contact point tip profile (example) Remarks
Square
groove
● Allows measurement of the diameter of variously shaped inside grooves and splines.
● Minimum measurable groove diameter is approximately 16mm (differs depending
on the workpiece profile.)
● Dimension should be as follows:
For W = less than 2mm: = less than 2mm
For W = 2mm or more: = 2mm as the standard value which can be modified
according to circumstances.
● The number of splines or serrations is limited to a multiple of 3.
● Details of the workpiece profile should be provided at the time of placing a custom-
order.
● If your application needs a measuring range different from that of the standard in-
ternal micrometer an additional initial cost for the master ring gage will be required.
Round
groove
Spline
Serration
Threaded
hole
● Allows measurement of the effective diameter of an internal thread.
● Measurable internal threads are restricted according to the type, nominal dimen-
sion, and pitch of the thread. Please contact Mitutoyo with the specification of the
thread to be measured for advice.
■ Custom-ordered Products (Holtest/Borematic)
Mitutoyo can custom-build an internal micrometer best-suited to your special application. Please feel free to contact Mitutoyo about the possibilities
- even if only one custom-manufactured piece is required. Please note that, depending on circumstances, such a micrometer will usually need to be
used with a master setting ring for accuracy assurance. (A custom-ordered micrometer can be made compatible with a master ring supplied by the
customer. Please consult Mitutoyo.)
* Mitutoyo can manufacture other custom designs of internal micrometer according to the application. Cost and delivery depends on the order
terms and conditions. To place a custom order please contact the nearest Mitutoyo Sales Center.
Internal Micrometers
Contact point
■ Nomenclature
Cone Spindle
Outer sleeve
Thimble
Ratchet stop
ød
øD
ød
øD
r
ø
d
øD
r
ø
d
øD
øD
W=0.5 or greater
l
Tip radius R that can measure the minimum
diameter (different for each size)
R=0.3 or greater
45˚ or more
W=1 or more
l
Radius=
0.5 or more
l
W=1 or more

Airy points (a ~ 0.577 )
Bessel points (a ~ 0.554 )
If an inside micrometer is misaligned in the axial or radial direction by
an offset distance X when a measurement is taken, as in Figures 1 and
2, then that measurement will be in error as shown in the graph below
(constructed from the formulae given above). The error is positive for
axial misalignment and negative for radial misalignment.
Figure 1
■ Misalignment Errors
■ Misalignment Errors
Figure 2
: Inside diameter to be measured
L: Length measured with axial offset X
X: Offset in axial direction
△ : Error in measurement
△ : L− =√ 2
+X2
−
■ Airy and Bessel Points
When a length standard bar or internal micrometer lies horizontally,
supported as simply as possible at two points, it bends under its own
weight into a shape that depends on the spacing of those points. There
are two distances between the points that control this deformation in
useful ways, as shown below.
The ends of a bar (or micrometer) can be made exactly horizontal by
spacing the two supports symmetrically as shown above. These points
are known as the ‘Airy Points’ and are commonly used to ensure that
the ends of a length bar are parallel to one another, so that the length
is well defined.
The change in length of a bar (or micrometer) due to bending can be
minimized by spacing the two supports symmetrically as shown above.
These points are known as the ‘Bessel Points’ and may be useful when
using a long inside micrometer.
■ Bore Gages
●Mitutoyo bore gages for small holes feature contact elements with
a large curvature so they can be easily positioned for measuring the
true diameter (in the direction a-a’) of a hole. The true diameter is the
minimum value seen on the dial gage while rocking the bore gage as
indicated by the arrow.
●The spring-loaded guide plate on a Mitutoyo two-point bore gage
automatically ensures radial alignment so that only an axial rocking
movement is needed to find the minimum reading (true diameter).
Graduation 0.005mm
(1)Outer sleeve 35 mm
(2)Thimble 0.015mm
Reading 35.015mm
(1)
(2)
Outer sleeve
Thimble
: Inside diameter to be measured
L: Length measured with radial offset X
X: Offset in radial direction
△ : Error in measurement
△ : L− =√ 2
–X2
−
a'
a
Anvil
Guide plate Contact point
Workpiece
a
a
10
9
8
7
6
5
4
3
2
1
0.10
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
�ℓ=200mm
ℓ=500mm
ℓ=1000mm
Error
(positive
for
axial,
and
negative
for
radial,
misalignment)
(mm)
Misalignment (offset) of one end of micrometer (mm)
X
X
L
L

16
Main scale
Reference surface
Vernier scale
Depth groove
Thumbwheel
Calipers
Inside jaws
Vernier Caliper
■ Nomenclature
Absolute Digimatic Caliper
■ Special Purpose Caliper Applications
Graduation 0.05mm
(1)Main scale 16 mm
(2)Vernier 0.15 mm
Reading 16.15 mm
Graduation 0.01mm
(1)Main scale 16 mm
(2)Dial 0.13 mm
Reading 16.13 mm
Depth measuring faces
Outside measuring faces
Inside measuring faces
Step measuring faces
Outside jaws
Screw, gib pressing
Gib, slider
Locking screw
Screw, gib setting
Beam Stop, slider
Depth bar
Slider
Outside measuring faces
Inside measuring faces
Step measuring faces
Depth measuring faces
Slider
Locking screw
Output connector
Beam
Depth bar
Inside jaws
Outside jaws
ZERO Set/ABSOLUTE button
Thumb-roller
Reference surface
Main scale
(1)
(2)
(1)
(2)
Depth bar
(1)
(2)
(2)
Point jaw caliper Offset jaw caliper Depth caliper Blade jaw caliper
For uneven surface measurement For stepped feature measurement For depth measurement For diameter of narrow groove measurement
Vernier scale
Main scale Dial
Main scale

■ Types of Vernier Scale
The Vernier scale is attached to the caliper’s slider and each division
on this scale is made 0.05mm shorter than one main scale division
of 1 mm. This means that, as the caliper jaws open, each successive
movement of 0.05mm brings the succeeding vernier scale line into
coincidence with a main scale line and so indicates the number of
0.05mm units to be counted (although for convenience the scale is
numbered in fractions of a mm). Alternatively, one vernier division
may be made 0.05mm shorter than two divisions of the main scale to
make a long vernier scale. This makes the scale easier to read but the
principle, and resolution, is still the same.
●Standard Vernier scale (resolution 0.05mm)
●Long Vernier scale (resolution 0.05mm)
Reading 1.45mm
Reading 30.35mm
■ Sources of Error
Main sources of error include scale misreading (parallax effect),
excessive measuring force causing jaw tilt, thermal expansion caused by
a temperature difference between the caliper and workpiece, and small-
hole diameter error caused by inside jaw offset. There are other minor
error sources such as graduation accuracy, reference edge straightness,
main scale flatness and squareness of the jaws. These sources are
allowed for within the specified accuracy of a new caliper and only
cause significant error in case of wear or damage.
The JIS standard emphasizes that care must be used to ensure that
measurement is performed with an appropriate and constant measuring
force, since a caliper has no constant-force device, and that the user
must be aware of the increased possibility of error due to measuring a
workpiece using the tips of the jaws (Abbe’s Principle).
■ Moving Jaw Tilt Error
If the moving jaw becomes tilted out of parallel with the fixed jaw,
either through excessive force being used on the slider or lack of
straightness in the reference edge of the beam, a measurement error
will occur as shown in the figure. This error may be substantial due to
the fact that a caliper does not conform to Abbe’s Principle.
Example: Assume that the error slope of the jaws due to tilt of the slider is 0.01mm in 50mm and
the outside measuring jaws are 40mm deep, then the error (at the jaw tip) is calculated as
(40/50)x0.01mm = 0.008mm.
If the guide face is worn then an error may be present even using the correct measuring
force.
■ About Long Calipers
Steel rules are commonly used to roughly measure large workpieces
but if a little more accuracy is needed then a long caliper is suitable for
the job. A long caliper is very convenient for its user friendliness but
does require some care in use. In the first place it is important to realize
there is no relationship between resolution and accuracy. Resolution is
constant whereas the accuracy obtainable varies dramatically according
to how the caliper is used.
The measuring method with this instrument is a concern since distortion
of the main beam causes a large amount of the measurement error,
so accuracy will vary greatly depending on the method used for
supporting the caliper at the time. Also, be careful not to use too much
measuring force when using the outside measuring faces as they are
furthest away from the main beam so errors will be at a maximum here.
This precaution is also necessary when using the tips of the outside
measuring faces of a long-jaw caliper.
■ Inside Measurement with a CM-type
Caliper
Because the inside measuring faces of a CM-type caliper are at the
tips of the jaws the measuring face parallelism is heavily affected by
measuring force, and this becomes a large factor in the measurement
accuracy attainable.
In contrast to an M-type caliper, a CM-type caliper cannot measure a
very small hole diameter because it is limited to the size of the stepped
jaws, although normally this is no inconvenience as it would be unusual
to have to measure a very small hole with this type of caliper. Of course,
the radius of curvature on the inside measuring faces is always small
enough to allow correct hole diameter measurements right down to the
lowest limit (jaw closure).
Mitutoyo CM-type calipers are provided with an extra scale on the slider
for inside measurements so they can be read directly without the need
for calculation, just as for an outside measurement. This useful feature
eliminates the possibility of error that occurs when having to add the
inside-jaw-thickness correction on a single-scale caliper.
f=hθ=h·a/ℓ
CM-type caliper CN-type caliper (with knife-edge)
For outside measurement
For measurement of inside bore
For outside measurement
For stepped feature measurement
h
h
a
θ
f

18
Height Gages
Vernier Height Gage
■ Nomenclature
Mechanical Digit Height Gage
Digimatic Height Gage
Main pole
Sub pole
Strut
Power ON/OFF key
Zero set button / ABS (Absolute) button
Preset mode, ball diameter
compensation mode button
Hold / data button
Number up/down button, presetting
Direction switch / digit shift
button, presetting
Reference surface, base
Base
Feed handle
Slider onit
Touch probe connector
Bracket, scriber
Scriber clamp
Measuring surface
Clamp box, scriber
Scriber
Battery cap
Column
Main pole
Sub pole
Strut
Column
Base
Feed handle
Slider clamp
Dial
Hand-pointer
Reset button
Counter, downward
Counter, upward
Slider
Bracket, scriber
Scriber clamp
Clamp box, scriber
Measuring face,
scriber
Scriber
Base
Reference surface, column
Measuring face,
scriber
Scriber
Bracket, scriber
Scriber clamp
Clamp box, scriber
Fine adjuster for main scale
Column
Main scale
Fine feed nut, slider
Clamp
Slider clamp
Vernier scale
Slider

122.11 125.11
■ How to read
●Vernier Height gage ●Dial Height gage
●Mechanical Digit Height gage
■ General notes on using the height
gage
1. Make sure that the base is free of burrs that would otherwise
adversely affect scribing and measuring stability. If there is a burr,
remove it by using an oilstone.
2. Keep the leaf spring of the slider and reference face of the main scale
clean. Accumulated dust might cause poor sliding.
3. Tighten the slider clamp to prevent the slider from moving during
scribing.
4. The scriber edge might move by up to 0.01 mm when the slider
clamp is tightened. Check the movement by using a test indicator.
5. The parallelism between the scriber mounting bracket, scriber
measuring face, and reference surface of the base is 0.01 mm or less.
Avoid moving the scriber forward or backwards during measurement
because movement can cause errors.
6. Use the fine feed to ensure accurate adjustment to final position.
7. Be aware of possible parallax error on vernier instruments and always
read the scales from the normal direction.
Measuring upwards from a reference surface Measuring downwards from a reference surface
Graduation 0.02mm
(1)Main scale 79 mm
(2)Vernier 0.36 mm
Reading 79.36 mm
Graduation 0.02mm
(1)Main scale 34 mm
(2)Dial 0.32 mm
Reading 34.32 mm
Counter 122 mm
Dial 0.11 mm
Reading 122.11 mm
Counter 125 mm
Dial 0.11 mm
Reading 125.11 mm
(2)
(1) (2)
(1)
Vernier scale
Main scale
Main scale
Dial
Scriber
Reference surface Scriber
Reference surface

20
Continuous dial: For direct reading
Balanced dial: For reading the difference from a reference surface
Reverse reading dial: For depth or bore gage measurement
One revolution dial: For error free reading of small differences
Dial Indicators/Dial Test Indicators
■ Nomenclature
■ Dial faces
0.01mm 0.001mm
Continuous dial (Dual reading) Balanced dial (Multi-revolution)
Continuous dial (Reverse reading) Balanced dial (One revolution)
Continuous dial (Dual reading) Balanced dial (Multi-revolution)
Continuous dial (Double scale spacing) Balanced dial (One revolution)
Cap
Bezel clamp
Stem
Spindle (or plunger)
Contact point
Dial face
Hand (or pointer)
Limit markers
Bezel

■ Mounting a Dial Indicator
■ Dial Indicator Contact Point
●Screw thread section is standardized on M2.5x0.45 (Length: 5mm).
●Incomplete thread section at the root of the screw shall be less than
0.7mm when fabricating a contact point.
Stem
mounting
Method
Note
● Mounting hole tolerance: ø8G7(+0.005 to 0.02)
● Clamping screw: M4 to M6
● Clamping position: 8mm or more from the lower edge of the stem
● Maximum clamping torque: 150N·cm when clamping with a single M5 screw
● Note that excessive clamping torque may adversely affect spindle movement.
● Mounting hole tolerance: ø8G7(+0.005 to 0.02)
Lug mounting
Method
Note
● Lugs can be changed 90 degrees in orientation according to the application. (The lug is set horizontally when shipped.)
● Lugs of some Series 1 models (Nos. 1911, 1913-10, & 1003), however, cannot be altered to horizontal.
● To avoid cosine-effect error, ensure that a dial indicator is mounted with its spindle in line with the intended measurement direction.
■ Dial gage and Digimatic indicator positions
■ Setting the origin of a Digimatic
indicator
Repeatability in the range of 0.2 mm from the end of the stroke
is not guaranteed for Digimatic indicators. When setting the zero
point or presetting a specific value, be sure to lift the spindle at
least 0.2 mm from the end of the stroke.
■ Notes on using dial gages and
Digimatic indicators
•Do not lubricate the spindle. Doing so might cause dust to
accumulate, resulting in a malfunction.
•If the spindle movement is poor, wipe the upper and lower spindle
surfaces with a dry or alcohol-soaked cloth. If the movement is not
improved by this cleaning, contact Mitutoyo for repair.
Position Remarks
Contact point down
(normal position)
—
Spindle horizontal
(lateral position)
If measurement is performed with the spindle horizontal or contact point up, the measuring force is less
than when the contact point is down. In this case be sure to check the operation and repeatability of
the indicator or digital display.
For guaranteed-operation specifications according to positions of Digimatic indicators and dial gages,
refer to the product descriptions in a general catalog.
Contact point up
(upside-down position)
Clamping the stem directly
with a screw
Clamping the stem
by split-body fastening
8mm or more
Plain washer
M6 screw
0.2mm
5
ø3 counterbore, depth 1mm
M2.5x0.45, depth 7mm
M2.5x0.45
Spindle
Incomplete thread section shall
be less than 0.7mm
Ground
Ground
Ground

22
Dial Indicators/Dial Test Indicators
■ Dial Indicator B7503-1997 (Extract from JIS/Japanese Industrial Standards)
No. Item Calibration method Diagram of calibration setup Tools for calibration
1
Indication
error
Holding the dial indicator with its spindle set vertically downward,
follow the procedure prescribed below and determine the error of
indication with reference to the dial graduations.
First, displace the spindle upward over the entire measuring range while
plotting errors at every 1/10 revolution of the pointer for the first two
revolutions from the zero point, at every half revolution for the next
five revolutions, and at every revolution after the fifth revolution, then
reverse the spindle displacement at the end of the measuring range of
the dial indicator and plot errors at the same points measured during
upward spindle displacement. Determine errors from a bidirectional
error curve thus obtained. (Fig. 1)
For 0.001mm or 0.002mm graduation dial indicators
with a 2mm measuring range or less: A micrometer head
or other measuring unit with 0.5µm graduation or less
and instrumental error of ±1µm and a supporting stand.
For dial indicators other than the above: A micrometer
head or other measuring unit with 1µm graduation
or less and ±1µm instrumental error and a supporting
stand.
2
Adjacent
error
3 Retrace error
4 Repeatability
Apply the contact point of the dial indicator perpendicularly to the
upper face of a measuring stage, displace the spindle quickly and slowly
five times at a desired position within the measuring range and deter-
mine the maximum difference between the five indications obtained.
Measuring stage
Supporting stand
5
Measuring
force
Holding a dial indicator with its spindle set vertically downward, displace
the spindle upward and then downward continuously and gradually
and take measurements of the measuring force at the zero, middle, and
end points in the measuring range in both the upward and downward
directions.
Supporting stand
Top pan type spring scale (graduation: 2gf or less) or
force gage (sensitivity: 0.02N or less)
Graduation and measuring range
0.01mm 0.002mm 0.001mm
Measuring range 10mm or less 2mm or less Over 2mm and up to 10mm 1mm or less Over 1mm and up to 2mm Over 2mm and up to 5mm
Retrace error 5 3 4 3 3 4
Repeatability 5 0.5 1 0.5 0.5 1
Indication
error
1/10 revolution *1
8 4 5 2.5 4 5
1/2 revolution ±9 ±5 ±6 ±3 ±5 ±6
One revolution ±10 ±6 ±7 ±4 ±6 ±7
Two revolutions ±15 ±6 ±8 ±4 ±6 ±8
Entire measuring range ±15 ±7 ±12 ±5 ±7 ±10
■ Maximum permissible error of indication Unit: µm
*1
: Adjacent accuracy
Remarks: Values in the table above apply at at 20˚C.
Performance: Maximum permissible errors of a dial indicator shall comply with the table above.
Permissible errors of indication shall be evaluated inclusive of the uncertainty of calibration.
Supporting stand
Dial indicator
Micrometer head or other
length measuring unit
Supporting stand
Measuring stage
Dial indicator
Top pan type
spring scale
Dial indicator
Supporting stand
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 6 7 8 9
0
0
+10
µm
+10
µm
0 0.5 1 1.5
Measuring range
2 revolutions
Range for two-revolution indication error and adjacent error
Range for 1/2-revolution indication error
Two-revolution indication error
Adjacent error
One-revolution indication error
1/2-revolution indication error
1/5-revolution or more
End point
Stroke
Rest point of the long pointer
Zero point
1/10-revolution or more
Retrace
Forward
Retrace error
Indication
error
Indication error over the
entire measuring range
10 revolutions
Range for one-revolution indication error

No. Item Calibration method Diagram of calibration setup Tools for calibration
1
Wide-range
accuracy
(1) For an indicator of 0.01 mm graduation: Displace the contact point so as to move the pointer
clockwise in increments of 0.1 mm with reference to the graduations from the zero point to
the end point of the measuring range while taking readings of the calibration tool at each
point and determine this accuracy from the error curve drawn by plotting the differences of
each "indicator reading - calibration tool reading".
(2) For an indicator of 0.002 mm graduation: Displace the contact point so as to move the pointer
clockwise in increment of 0.02 mm with reference to the graduations from the zero point to
the end point of the measuring range while taking readings of the calibration tool at each
point and determine this accuracy from the error curve drawn by plotting the differences of
each "indicator reading - calibration tool reading". The instrumental error of the calibration
tool shall be compensated prior to this measurement.
Micrometer head or
measuring unit (graduation:
1µm or less, instrumental
error: within ±1µm), sup-
porting stand
2 Adjacent error
3 Retrace error
After the completion of the wide-range accuracy measurement, reverse the contact point from
the last point of measurement while taking readings at the same scale graduations as for the
wide-range accuracy measurement and determine the retrace error from the error curve plotted.
4 Repeatability
a
Holding the dial test indicator with its stylus parallel with the top face of the measuring stage,
displace the contact point quickly and slowly five times at a desired position within the measuring
range and determine the maximum difference in indication.
Measuring stage, Support-
ing stand, and Gauge block
of grade 1 as stipulated by
JIS B7506 (Gauge block)
b
Holding the stylus parallel to a gauge block placed on the measuring stage, move the gauge block
to and fro and left to right under the contact point within the measuring range and determine the
maximum difference in indication.
5 Measuring force
Holding an indicator by the case or stem, displace the contact point gradually and continuously
in the forward and backward directions respectively and take a reading of measuring force at the
zero, middle and end points of the measuring range in each direction.
●Performance
The maximum measuring force in the forward direction shall not exceed 0.5N. The difference
between the maximum and minimum measuring forces in one direction shall not exceed 0.2N
(20gf). Note that the smallest possible measuring force is desirable for indicators.
Top pan type spring scale
(graduation: 2gf or less)
or force gage (sensitivity:
0.02N or less)
The reading of any indicator will not represent an accurate measurement if its
measuring direction is misaligned with the intended direction of measurement
(cosine effect). Because the measuring direction of a dial test indicator is at right
angles to a line drawn through the contact point and the stylus pivot, this effect
can be minimized by setting the stylus to minimize angle θ (as shown in the
figures). If necessary, the dial reading can be compensated for the actual θ value
by using the table below to give the true measurement.
True measurement = dial reading x compensation value
Examples
If a 0.200mm measurement is indicated on the dial at
various values of θ, the true measurements are:
For θ=10˚, 0.200mm×.98=0.196mm
For θ=20˚, 0.200mm×.94=0.188mm
For θ=30˚, 0.200mm×.86=0.172mm
■ Dial Test Indicator B7533-1990 (Extract from JIS/Japanese Industrial Standards)
●Accuracy of indication
Permissible indication errors of dial test indicators are as per the table below. (Unit: µm)
Graduation (mm) Measuring range (mm) Wide range accuracy Adjacent error Repeatability Retrace error
0.01
0.5 5
5 3
3
0.8 8
1.0 10 4*1
0.002
0.2
3 2 1 2
0.28
*1
: Applies to indicators with a contact point over 35 mm long.
Remarks: Values in the table above apply at 20°C.
■ Dial Test Indicators and the Cosine Effect
Compensating for a non-zero angle
Angle Compensation value
10˚ 0.98
20˚ 0.94
30˚ 0.86
40˚ 0.76
50˚ 0.64
60˚ 0.50
Note: A special contact point of involute form can be used to apply compensation automatically and allow
measurement to be performed without manual compensation for any angle θ from 0 to 30˚. (This type of contact
point is custom-made.)
Supporting stand
Micrometer head or
length measuring unit
Dial test indicator
Dial test indicator
Measuring stage
Supporting stand
Gauge block Measuring stage
Dial test indicator
Top pan type
spring scale
θ
θ
θ
θ

24
Gauge Blocks
■ Definition of the Meter
The 17th General Conference of Weights and Measures in 1983
decided on a new definition of the meter unit as the length of the path
traveled by light in a vacuum during a time interval of 1/299 792 458 of
a second. The gauge block is the practical realization of this unit and as
such is used widely throughout industry.
■ Selection, Preparation and Assembly
of a Gauge Block Stack
Select gauge blocks to be combined to make up the size required for
the stack.
(1) Take the following things into account when selecting gauge blocks.
a. Use the minimum number of blocks whenever possible.
b. Select thick gauge blocks whenever possible.
c. Select the size from the one that has the least significant digit
required, and then work back through the more significant digits.
(2) Clean the gauge blocks with an appropriate cleaning agent.
(3) Check the measuring faces for burrs by using an optical flat as
follows:
Note:The abrasive surface of a Ceraston must be made flat by lapping it from time to time.
After lapping the Ceraston, the lapping powder must be completely removed from the
stone to prevent the surface of the gauge block being scratched.
Mitutoyo does not supply the Arkansas stone.
a. Wipe each measuring face clean.
b. Gently place the optical flat on the gauge block measuring face.
c. Lightly slide the optical flat until interference fringes appear.
Judgment 1: If no interference fringes appear, it is assumed that
there is a large burr or contaminant on the
measuring face.
d. Lightly press the optical flat to check that the interference fringes
disappear.
Judgment 2: If the interference fringes disappear, no burr exists
on the measuring face.
Judgment 3: If some interference fringes remain locally while
the flat is gently moved to and fro, a burr exists
on the measuring face. If the fringes move along
with the optical flat, there is a burr on the optical
flat.
(4) Apply a very small amount of oil to the measuring face and spread
it evenly across the face. (Wipe the face until the oil film is almost
removed.) Grease, spindle oil, vaseline, etc., are commonly used.
e. Remove burrs, if any, from the measuring face using a flat, fine-
grained abrasive stone.
1 Wipe off any dust or oil from the gauge block and the
Ceraston (or Arkansas stone) using a solvent.
2 Place the gauge block on the Ceraston so that the measuring
face that has burrs is on the abrasive surface of the stone.
While applying light pressure, move the gauge block to and fro
about ten times (Fig. 1). Use a block rubber for thin gauge
blocks to apply even pressure (Fig. 2).
3 Check the measuring face for burrs with an optical flat. If the
burrs have not been removed, repeat step (2). If burrs are too
large to be removed with a stone, discard the gauge block.
(Fig. 1)
(Fig. 2)
CERASTON
(Arkansas stone)
Rubber
CERASTON
(Arkansas stone)

■ Thermal Stabilization Time
The following figure shows the degree of dimensional change when
handling a 100mm steel gauge block with bare hands.
(5) Gently overlay the faces of the gauge blocks to be wrung together.
There are the following three methods depending on the size of wringing:
A.
Wringing thick
gauge blocks
B.
Wringing a thick gauge
block to a thin gauge block
b.
Wringing thin gauge blocks
Cross the gauge blocks at 90˚ in the
middle of the measuring faces.
Overlap one side of a thin gauge block
on one side of a thick gauge block.
To prevent thin gauge blocks from bending, first
wring a thin gauge block onto a thick gauge block.
Rotate the gauge blocks while applying
slight force to them. You will get a sense
of wringing by sliding the blocks.
Slide the thin gauge block while pressing
the entire overlapped area to align
the measuring faces with each other.
Then, wring the other thin gauge
block onto the first thin gauge block.
Align the measuring faces with each other.
Apply an optical flat to the surface of the thin
gauge block to check the wringing state.
Finally, remove the thick
gauge block from the stack.
Irregular
interference fringes
Wipe the exposed measuring face(s) and continue building up
the stack, in the same manner as above, until complete.
The stack can then be thermally stabilized on a surface plate before
use, if required. Do not leave the stack assembled for longer than
is necessary, and clean and apply rustproofing protection to the
blocks before packing them away in their box after use.
Time fingers are released
The gauge block is held with five fingers.
5
1
2
3
4
5
6
7
8
9
10 20 30 40 50 60 70
Elongation
(µm)
Lapse of time (minutes)
The gauge block is held with three fingers.

26
Laser Scan Micrometers and Laser Indicators
a. Distance between lines C and D
→ X alignment
■ Compatibility
Every LSM Measuring Head is supplied with an ID Unit and they must
always be used together. The ID Unit carries the same serial number as
the Emission Unit and is inserted into the chosen display unit before
use. However, the 500S series LSM is not compatible with older models
(LSM-3000, 3100, 4000, 4100, 400, 500, and 500H series).
■ Workpieces and Measurement
Conditions
A measurement error may be caused due to the difference between
visible and invisible lasers and depending on the shape or surface
roughness of a workpiece. To minimize this possibility, calibrate the
instrument using a master of the same shape and the same value of
surface roughness as the workpiece whenever possible. If measured
values vary greatly depending on the measurement conditions, it is
possible to improve accuracy by making as many measurements as
possible and averaging the results.
■ Noise Suppression
To prevent malfunction due to electrical interference, do not run an
LSM’s signal cable or relay cable alongside a cable subject to high
voltage or high surge currents. The LSM unit must be grounded.
■ Connecting to a Computer
When connecting an LSM to a computer via an RS-232C interface,
ensure that the connector pins are wired correctly.
■ Laser Beam Alignment
To minimize errors due to laser-beam misalignment when using those
models that can be disassembled and built into jigs and fixtures, ensure
that the emission and reception unit axes are aligned and spaced
according to the following specification for the particular model:
■ Aligning the optical axes in the horizontal plane
(using the hole patterns in the bases)
b. Angle between lines C and D
→ qx alignment
c. Distance between planes A and B
→ Y alignment
■ Aligning the optical axes in the vertical plane (using
the base mounting surfaces)
d. Angle between planes A and B
→ qy alignment
Application
Model
Distance between emission
unit and reception unit
X and Y qx and qy
LSM-501S
68mm or less within 0.5mm within 0.4˚ (7mrad)
100mm or less within 0.5mm within 0.3˚ (5.2mrad)
LSM-503S
135mm or less within 1mm within 0.4˚ (7mrad)
350mm or less within 1mm within 0.16˚ (2.8mrad)
LSM-506S
LSM-512S
LSM-516S 800mm or less within 1mm within 0.09˚ (1.6mrad)
l Permissible unit spacing and optical axis
misalignment limits
X
Reference line C
Reference line D
x
Reference line C
Reference line D
Y
Reference surface A
Reference surface B
y
Reference surface A
Reference surface B

Simultaneous measurement of the diameter
and deflection of a roller
Measurement of thickness variation of a film
or sheet (at dual points)
Measurement of thickness of a film or sheet
Continuous measurement of tape width
■ Measurement Examples
Simultaneous measurement of X and Y of an
electric wire, optical fiber, or roller
Measurement of pin pitch, width, or gap of
an IC component
Measurement of displacement of an optical
disk magnetic disk head
Dual system for measuring a large outside
diameter
■ Safety Precautions
The LSM uses a low-power visible laser beam for measurement, which
conforms to Class 2 of JIS C 6802 "Safety Standard for Emission from a
Laser Product". The Class 2 Caution/Description label as shown below is
affixed to those parts related to measurement.
Deﬂection
Reference
edge
Outside diameter
Reference blade
Reference edge
Reference edge

28
Linear Gages
■ Precautions in Mounting a Gage Head
●Insert the stem of the gage into the mounting clamp of a measuring
unit or a stand and tighten the clamp screw.
●Notice that excessively tightening the stem can cause problems with
spindle operation.
●Never use a mounting method in which the stem is clamped by direct
contact with a screw.
●Never mount a linear gage by any part other than the stem.
●Mount the gage head so that it is in line with the intended direction
of measurement. Mounting the head at an angle to this direction will
cause an error in measurement.
●Exercise care so as not to exert a force on the gage through the
cable.
■ Plain Stem and Stem with Clamp Nut
The stem used to mount a linear gage head is classified as a "plain
type" or "clamp nut type" as illustrated below. The clamp nut stem
allows fast and secure clamping of the linear gage head. The plain stem
has the advantage of wider application and slight positional adjustment
in the axial direction on final installation, although it does requires a
split-fixture clamping arrangement or adhesive fixing. However, take
care so as not to exert excessive force on the stem.
■ Measuring Force
This is the force exerted on a workpiece during measurement by the
contact point of a linear gage head, at its stroke end, expressed in
Newtons.
■ Comparative Measurement
A measurement method where a workpiece dimension is found by
measuring the difference in size between the workpiece and a master
gage representing the nominal workpiece dimension. ●Machine the clamping hole so that its axis is parallel with the
measuring direction. Mounting the gage at an angle will cause a
measuring error.
●When fixing the Laser Hologage, do not clamp the stem too tightly.
Over-tightening the stem may impair the sliding ability of the spindle.
●If measurement is performed while moving the Laser Hologage,
mount it so that the cable will not be strained and no undue force
will be exerted on the gage head.
■ Precautions in Mounting a Laser
Hologage
To fix the Laser Hologage, insert the stem into the dedicated stand or
fixture.
Recommended hole diameter on the fixing side: 15mm +0.034/-0.014
■ Zero-setting
A display value can be set to 0 (zero) at any position of the spindle.
■ Presetting
Any numeric value can be set on the display unit for starting the count
from this value.
■ Direction changeover
The measuring direction of the gage spindle can be set to either plus (+)
or minus (-) of count.
■ MAX, MIN, TIR Settings
The display unit can hold the maximum (MAX) and minimum (MIN)
values, and MAX - MIN value during measurement.
Head
Display Unit
Stem with clamp nut Plain stem
Stem Stem
Clamp screw Clamp screw
Clamp Clamp
0.000 0.000
0.000
1.234 123.456
Datum plane
+/-
MAX
MIN
Runout value (TIR) = MAX - MIN

■ Tolerance Setting
Tolerance limits can be set in various display units for automatically
indicating if a measurement falls within those limits.
■ Open Collector Output
An external load, such as a relay or a logic circuit, can be driven from
the collector output of an internal transistor which is itself controlled by
a Tolerance Judgement result, etc.
■ Digimatic Code
A communication protocol for connecting the output of measuring
tools with various Mitutoyo data processing units. This allows output
connection to a Digimatic Mini Processor DP-1VR for performing various
statistical calculations and creating histograms, etc.
■ BCD Output
A system for outputting data in binary-coded decimal notation.
■ RS-232C Output
A serial communication interface in which data can be transmitted bi-
directionally under the EIA Standards.
For the transmission procedure, refer to the specifications of each
measuring instrument.
Multi-point measurement can be performed by connecting multiple EH or EV counters with RS-link cables.
■ RS Link for EH Counter
It is possible to connect a maximum of 10 counter units and handle up to 20 channels of multi-point measurement at a time.
For this connection use a dedicated RS link cable No.02ADD950 (0.5m), No.936937 (1m) or No.965014 (2m). (The total length of RS link cables per-
mitted for the entire system is up to 10m.)
■ RS Link for EV Counter
It is possible to connect a maximum of 10* counter units and handle up to 60 channels of multi-point measurement at a time.
For this connection use a dedicated RS link cable No.02ADD950 (0.5m), No.936937 (1m) or No.965014 (2m). (The total length of RS link cables per-
mitted for the entire system is up to 10m.)
* The maximum number of counter units that can be connected is limited to 6 (six) if an EH counter is included in the chain.
RS Link Function
Personal computer
IN
RS-232C connector
First counter
RS-232C cable
01
Gage number 02 03 04……
Last counter
OUT IN
RS-232C connector
OUT IN
RS-232C connector
OUT
Personal computer
IN
RS-232C connector
Unit 2
RS-232C cable
01
Gage number 06 07 12……
…… ……
OUT IN OUT IN OUT
External display unit 1 External display unit 2
IN OUT
Unit 1
RS-232C connector

30
Linear Scales
1. Testing within the service temperature range
Confirms that there is no performance abnormality of a unit within
the service temperature range and that data output is according to the
standard.
2. Temperature cycle (dynamic characteristics) test
Confirms that there is no performance abnormality of a unit during
temperature cycling while operating and that data output is according
to the standard.
3. Vibration test (Sweep test)
Confirms that there is no performance abnormality of a unit while
subject to vibrations of a frequency ranging from 30Hz to 300Hz with a
maximum acceleration of 3g.
4. Vibration test (Acceleration test)
Confirms that there is no performance abnormality of a unit subject to
vibrations at a specific, non-resonant frequency.
5. Noise test
This test conforms to the following
EMC Directives:
EN550111991: Group 1, Class B
EN50082-1: 1992
6. Package drop test
This test conforms to JISZ0200 (Heavy duty material drop test)
■ Line driver output
This output features fast operating speeds of several tens to several
hundreds of nanoseconds and a relatively long transmission distance of
several hundreds of meters. A differential voltmeter line driver (RS422A
compatible) is used as an I/F to the NC controller in the linear scale
system.
■ RS-232C
An interface standard that uses an asynchronous method of serial
transmission of bits over an unbalanced transmission line for data
exchange between transmitters located relatively close to each other.
It is a means of communication mainly used for connecting a personal
computer with peripherals.
■ Binary output
Refers to output of data in binary form (ones and zeros) that represent
numbers as integer powers of 2.
■ Numerical control
Refers to a type of control that controls the tool position relative to
a workpiece to be machined with corresponding numerical control
commands.
■ Sequence control
Refers to a type of control that sequentially performs control step by
step according to the prescribed order of control.
■ Restoring the origin point
A function that stops each axis of a machine accurately in position
specific to the machine while slowing it with the aid of integrated limit
switches.
■ Origin offset
A function that enables the origin point of a coordinate system to be
translated to another point offset from the fixed origin point. For this
function to work, a system needs a permanently stored origin point.
■ Incremental system
A measurement mode in which a point measurement is made relative to
the point measured immediately before the current one.
■ Accuracy
The accuracy specification refers to the maximum difference between
the indicated and true positions at any point, within the range of
a scale, at a temperature of 20ºC. Since there is no international
standard defined for scale units, each manufacturer has a specific way
of specifying accuracy. The accuracies given in our catalog have been
determined using laser interferometry.
■ RS-422
An interface standard that uses serial transmission of bits in differential
form over a balanced transmission line. RS-422 is superior in its data
transmission characteristics and in its capability of operating with only a
single power supply of +5V.
■ BCD
A notation of expressing the numerals 0 through 9 for each digit
of a decimal number by means of four-bit binary sequence. Data
transmission is one-way output by means of TTL or open collector.
■ Absolute system
A measurement mode in which every point measurement is made
relative to a fixed origin point.
Tests for Evaluating Linear Scales
Glossary

Upon supply of power to a linear scale, position readings from three capacitance-type sub-scales
(COArse, MEDium and FINe) and one from a photoelectric sub-scale (OPTical) are taken. These sub-
scales use such a combination of pitches, and are so positioned relative to each other, that the readings
at any one position form a unique set and allow a microprocessor to calculate the position of the read
head on the scale to a resolution of 0.05μm.
Figure 1
1.Hyperfine gratings
Very fine-pitched scale grids (0.5μm) are used
in hologram analysis. These grids are much
finer than the conventional lithographic grids
used in reduction-exposure systems (1/15th
to 1/200th the thickness of lithography grids).
Hologram technology is essential to achieving
high resolution in measuring scales.
As shown in Figure A, interference of light
takes place three-dimensionally at the point
of intersection when two parallel laser beams
(a) and (b) intersect, generating interference
fringes. The pitch of the interference fringes
is approximately the same as that of the
wavelength of light and exactly measures
0.5µm for the Mitutoyo hologram scale. This
allows an extra-fine pitch scale to be made by
recording the interference fringes.
■ Narrow range accuracy
Scale gratings marked on a scale unit normally adopt 20µm per pitch
though it varies according to the kind of scale. The narrow range
accuracy refers to the accuracy determined by measuring one pitch of
each grating at the limit of resolution (1µm for example).
■ Principle of the Absolute Linear Scale
(Example: AT300, 500-S/H)
■ A laser holo-scale provides accurate measurements... why?
2.Diffraction is fundamental
The mechanism of light diffraction is used
to detect scale displacement as a change
in the phase of light. Since the amount of
phase change is equivalent to the hologram’s
grid pitch, an accurate length-measurement
system can be created to detect scale
displacement in 0.5μm steps.
As shown in Figure B, a light beam (a) is
diffracted by the hologram grid and becomes
a diffracted light beam (b). When the scale
moves by a quarter of the hologram’s grid
pitch, the diffracted light beam (b) shows the
equivalent change in the phase of light, as the
light beam (b’)
3.Complete sinewaves are best
Displacement is detected via the interference
of diffracted light, in the form of bright-to-
dark signals with a pitch equal to one-half
that of the hologram grid (0.25μm). Unlike
ordinary scales which use quasi-sinewaves,
signals available with this scale are complete
sinewaves, which are extremely immune to
division error and regarded as a key factor for
high resolution.
Since it is impossible to directly detect a phase
shift of light with
current technology,
two diffracted
light beams are
transformed by
means of interference
into dark-light signals
to be detected as
shown in Figure C.
Dividing the obtained
signals by 250 makes
it possible to measure
down to 1nm.
To identify the
direction of scale displacement, two light
receptors (a) and (b) are used to detect one
light beam as a signal having a 90-degree
phase difference from the other.
(a)
(b)
0.5µm
Figure A
1P
1/4P
1
/
4
P
L
i
g
h
t
(
b
’
)
L
i
g
h
t
(
a
)
L
i
g
h
t
(
b
)
Figure B
Figure C
(a) (b)
Scale
3768mm
OPT
COA
MED
FIN
3768mm
58.88mm
0.92mm
20µm
(512)
(512)
(400) 0.05µm
7.36mm
0.115mm
(512) Approx. 1.8µm
Resolution
Electrostatic
capacitance
type
Photo-electronic
type
Signal cycle (interpolation)

32
Profile Projectors
■ Erect Image and Inverted Image
An image of an object projected onto a screen is erect if it is orientated
the same way as the object on the stage. If the image is reversed top
to bottom, left to right and by movement with respect to the object on
the stage (as shown in the figure below) it is referred to as an inverted
image (also known as a reversed image, which is probably more
accurate).
ΔM(%): Magnification accuracy expressed as a percentage of the
nominal lens magnification
L: Length of the projected image of the reference object mea-
sured on the screen
: Length of the reference object
M: Magnification of the projection lens
■ Magnification Accuracy
The magnification accuracy of a projector when using a certain lens is
established by projecting an image of a reference object and comparing
the size of the image of this object, as measured on the screen, with
the expected size (calculated from the lens magnification, as marked)
to produce a percentage magnification accuracy figure, as illustrated
below. The reference object is often in the form of a small, graduated
glass scale called a `stage micrometer’ or `standard scale’, and the
projected image of this is measured with a larger glass scale known as a
`reading scale’.
(Note that magnification accuracy is not the same as measuring accuracy.)
■ Telecentric Optical System
An optical system based on the principle that the principal ray is aligned
parallel to the optical axis by placing a lens stop on the focal point on
the image side. Its functional feature is that the center of an image will
not vary in size though the image blurs even if the focal point is shifted
along the optical axis.
For measuring projectors and measuring microscopes, an identical effect
is obtained by placing a lamp filament at the focal point of a condenser
lens instead of a lens stop and illuminating with parallel beams. (See the
figure below.)
ΔM(%)=((L− M) / M) X 100
F
F
An erect image
F
F
An inverted image
Projection screen
Top of the stage
F Workpiece
X-axis movement
Y-axis movement
Optical axis
Projection lens
Focal point on the image side
Contour illumination
Condenser lens Workpiece Projection
screen surface
Principal ray
Object surface
Light source
(lamp)

■ Type of Illumination
●Contour illumination: An illumination method to observe a workpiece
by transmitted light and is used mainly for measuring the magnified
contour image of a workpiece.
●Coaxial surface illumination: An illumination method whereby a
workpiece is illuminated by light transmitted coaxially to the lens
for the observation/measurement of the surface. (A half-mirror or a
projection lens with a built-in half-mirror is needed.)
●Oblique surface illumination: A method of illumination by obliquely
illuminating the workpiece surface. This method provides an image
of enhanced contrast, allowing it to be observed three-dimensionally
and clearly. However, note that an error is apt to occur in dimensional
measurement with this method of illumination.
(An oblique mirror is needed. Models in the PJ-H30 series are
supplied with an oblique mirror.)
■ Field of view diameter
The diameter of a workpiece projected onto the projection screen.
[Example]
If a 5X projection lens is used for a projector with a projection screen
of ø500mm:
Field of view diameter is given by 500mm/5 = ø100mm
Field of view diameter (mm) = Screen diameter of profile projector
Magnification of projection lens used
■ Working distance
Refers to the distance from the face of the projection lens to the surface
of a workpiece in focus. It is represented by symbol L2 in the diagram
below.
Projection lens
Half-mirror
Workpiece stage Workpiece
L2

34
Microscopes
■ Working Distance (W.D.)
The distance between the front end of a microscope objective and the
surface of the workpiece at which the sharpest focusing is obtained.
R=l/2·NA (µm)
l=0.55μm is often used as the reference wavelength
■ Resolving Power (R)
The minimum detectable distance between two image points,
representing the limit of resolution. Resolving power (R) is determined
by numerical aperture (NA) and wavelength (λ) of the illumination.
■ Parfocal Distance
The distance between the mounting position of a microscope objective
and the surface of the workpiece at which the sharpest focusing is
obtained. Objective lenses mounted together in the same turret should
have the same parfocal distance so that when another objective is
brought into use the amount of refocussing needed is minimal.
■ Infinity Optical System
An optical system where the objective forms its image at infinity and a
tube lens is placed within the body tube between the objective and the
eyepiece to produce the intermediate image. After passing through the
objective the light effectively travels parallel to the optical axis to the
tube lens through what is termed the ìnfinity space’ within which auxil-
iary components can be placed, such as differential interference contrast
(DIC) prisms, polarizers, etc., with minimal effect on focus and aberration
corrections.
■ Finite Optical System
An optical system that uses an objective to form the intermediate image
at a finite position. Light from the workpiece passing through the objec-
tive is directed toward the intermediate image plane (located at the front
focal plane of the eyepiece) and converges in that plane.
■ Real Field of View
(1)Diameter of surface observed through eyepiece
Real field of view = Eyepiece field number/Objective magnification
Example: Real field of view of 10X lens (ø2.4 eyepiece)=24/10=2.4
(2)Diameter of surface observed on video monitor
Real field of view=Size(length x width) of CCD camera pickup device/
Objective magnification
*Size (length x width) of 1/2-inch CCD camera pickup device=4.8x6.4
Example: Real field of view of 1X lens (length x width)=4.8x6.4
Real field of view of 10X lens (length x width)=0.48X0.64
■ Focal Length (f)
The distance from the principal point to the focal point of a lens: if
f1 represents the focal length of an objective and f2 represents the
focal length of an image forming (tube) lens then magnification is
determined by the ratio between the two. (In the case of the infinity-
correction optical system.)
Objective magnification = Focal length of the image-forming
(tube) lens/Focal length of the objective
Examples: 1X=200/200
10X=200/20
■ Numerical Aperture (NA)
The NA figure is important because it indicates the resolving power
of an objective lens. The larger the NA value the finer the detail that
can be seen. A lens with a larger NA also collects more light and will
normally provide a brighter image with a narrower depth of focus than
one with a smaller NA value.
NA=n·Sinθ
The formula above shows that NA depends on n, the refractive index
of the medium that exists between the front of an objective and the
specimen (for air, n=1.0), and angle θ, which is the half-angle of the
maximum cone of light that can enter the lens.
unit: mm
unit: mm
Light from point source is focused
at the intermediate image plane
Magnification of the objective = L2/L1
Objective lens
L1 L2
A point-source on
the workpiece
Objective lens
Image forming (tube) lens
Light from point source is focused
at the intermediate image plane
f1 f2 Magnification of the objective = f2/f1
A point-source on
the specimen
Infinity space
Working distance
Parfocal distance

■ Focal Point
Light rays from an object traveling parallel to the optical axis of a
converging lens system and passing through that system will converge
(or focus) to a point on the axis known as the rear focal point, or image
focal point.
■ Magnification
The ratio of the size of a magnified object image created by an
optical system to that of the object. Magnification commonly refers to
lateral magnification although it can mean lateral, vertical, or angular
magnification.
■ Apochromat Objective and Achromat
Objective
An apochromat objective is a lens corrected for chromatic aberration
(color blur) in three colors (red, blue, yellow).
An achromat objective is a lens corrected for chromatic aberration in
two colors (red, blue).
■ Bright-field Illumination and Dark-
field Illumination
In brightfield illumination a full cone of light is focused by the objective
on the specimen surface. This is the normal mode of viewing with an
optical microscope. With darkfield illumination, the inner area of the
light cone is blocked so that the surface is only illuminated by light from
an oblique angle. Darkfield illumination is good for detecting surface
scratches and contamination.
■ Depth of Focus (DOF)
Also known as ‘depth of field’, this is the distance (measured in the
direction of the optical axis) between the two planes which define the
limits of acceptable image sharpness when the microscope is focused
on an object. As the numerical aperture (NA) increases, the depth of
focus becomes shallower, as shown by the expression below:
DOF= l/2·(NA)2
l = 0.55μm is often used as the reference
wavelength
Example: For an M Plan Apo 100X lens (NA = 0.7), and light
wavelength of 0.55μm, the depth of focus of this objective is 0.55/(2
x 0.72
) = 0.6μm.
■ Principal Ray
A ray considered to be emitted from an object point off the optical
axis and passing through the center of an aperture diaphragm in a lens
system.
■ Aperture Diaphragm
An adjustable circular aperture which controls the amount of light
passing through a lens system. It is also referred to as an aperture stop
and its size affects image brightness and depth of focus.
■ Field Stop
A stop which controls the field of view in an optical instrument.
■ Telecentric System
An optical system where the light rays are parallel to the optical
axis in object and/or image space. This means that magnification is
nearly constant over a range of working distances, therefore almost
eliminating perspective error.
■ Erect Image
An image in which the orientations of left, right, top, bottom and
moving directions are the same as those of a workpiece on the
workstage.
■ Field Number
The field of view size (diameter) of an eyepiece, expressed in millimeters.
■ Precautions in Using a Microscope for
YAG Laser Machining
Laser machining with a microscope is used on thin films such as
semiconductors and liquid crystals, but high-power laser radiation
cannot be transmitted through a normal objective lens. Therefore, if
using a YAG laser, limit the laser power output as follows:
YAG laser wavelength Irradiation energy density (output) Pulse width Applicable objective
1064nm 0.2J/cm2
10ns M Plan NIR
532nm 0.1J/cm2
10ns M Plan NUV
355nm 0.05J/cm2
10ns
266mm 0.04J/cm2
10ns M Plan UV
* If the pulse width of a laser becomes shorter, the irradiation energy density is reduced by the root
of the ratio of the pulse widths.
Example: If the pulse width decreases to 1/4, the energy density is reduced to approximately 1/2.
Note: When intending to use a laser with a microscope, contact the nearest Mitutoyo Sales Center
beforehand to prevent unexpected damage to equipment and materials.
unit: µm

36
Detecting/measuring the edge in the XY plane
Gray
scale
255
127
0
Tool
(1) (2) (3)
Tool position
244 241 220 193 97 76 67 52 53 53
243 242 220 195 94 73 66 54 53 55
244 246 220 195 94 75 64 56 51 50
Vision Measuring Machines
■ Vision Measurement
Vision measuring machines mainly provide the
following processing capabilities.
■ Edge detection
■ Auto focusing
Focusing and Z measurement
■ Pattern recognition
Alignment, positioning, and checking a feature
■ Image Storage
An image is comprised of a regular array of pixels. This is just like a
picture on fine plotting paper with each square solid-filled differently.
■ Gray Scale
A PC stores an image after internally converting it to numeric values.
A numeric value is assigned to each pixel of an image. Image quality
varies depending on how many levels of gray scale are defined by the
numeric values. The PC provides two types of gray scale: two-level and
multi-level. The pixels in an image are usually displayed as 256-level gray
scale.
Pixels in an image brighter than a given level
are displayed as white and all other pixels are
displayed as black.
Each pixel is displayed as one of 256 levels
between black and white. This allows high-
fidelity images to be displayed.
■ Difference in Image Quality
Difference between 2-level and 256-level gray-scale images
Sample image displayed in 2-level gray scale Sample image displayed in 256-level gray scale
■ Variation in Image Depending on
Threshold Level
These three pictures are the same image displayed as 2-level gray scale
at different slice levels (threshold levels). In a 2-level gray-scale image,
different images are provided as shown above due to a difference in
slice level. Therefore, the 2-level gray scale is not used for high-precision
vision measurement since numeric values will change depending on the
threshold level that is set.
■ Dimensional Measurement
An image consists of pixels. If the number of pixels in a section to be
measured is counted and is multiplied by the size of a pixel, then the
section can be converted to a numeric value in length. For example,
assume that the total number of pixels in the lateral size of a square
workpiece is 300 pixels as shown in the figure below.
If a pixel size is 10μm under imaging magnification, the total length of
the workpiece is given by 10μm x 300 pixels = 3000μm = 3mm.
■ Edge Detection
How to actually detect a workpiece edge in an image is described using
the following monochrome picture as an example. Edge detection is
performed within a given domain. A symbol which visually defines
this domain is referred to as a tool. Multiple tools are provided to suit
various workpiece geometries or measurement data.
The edge detection system scans within the tool area as
shown in the figure at left and detects the boundary between
light and shade.
Example of numeric values assigned to pixels on the tool
(1) Scan start position
(2) Edge detection position
(3) Scan end position
1
0
255
127
0
2-level
gray scale
White
Gray
Black
Multi-level
gray scale
White
Gray
Black
300 pixels
10µm
480
pixels
CCD
camera
lens
Video signal
Ampliﬁer
High-speed A/D converter
Frame grabber
Display
screen
PC
640 pixels

■ High-resolution Measurement
As the image processing for increasing the resolution of edge detection,
sub-pixel processing is used.
Edge is detected by determining interpolation curve from adjacent pixel
data as shown below.
As a result, it allows measurement with resolution higher than 1 pixel.
■ Measurement along Multiple Portions
of an Image
Large features that cannot be contained on one screen have to be
measured by precisely controlling the position of the CCD sensor and
stage so as to locate each reference point within individual images. By
this means the system can measure even a large circle, as shown below,
by detecting the edge while moving the stage across various parts of
the periphery.
■ Determining a Measurement Point
Measuring machine stage
position
M = (Mx, My, Mz)
Detected edge position (from
the center of vision)
V = (Vx, Vy)
Actual coordinates are given by X = (Mx + Vx), Y = (My + Vy),
and Z = Mz, respectively.
Since measurement is performed while individual measured positions
are stored, the system can measure dimensions that cannot be included
in one screen, without problems.
■ Principle of Auto Focusing
The system can perform XY-plane measurement, but cannot perform
height measurement only from the CCD camera image. The system is
commonly provided with the Auto Focus (AF) mechanism for height
measurement. The following explains the AF mechanism that uses a
common image, although some systems may use an AF laser.
The system analyzes an image while
moving the CCD up and down in the Z
axis. In the analysis of image contrast,
an image in sharp focus will show a
peak contrast and one out of focus
will show a low contrast. Therefore,
the height at which the image contrast
peaks is the just in-focus height.
■ Variation in Contrast Depending on
the Focus Condition
Edge contrast is low due to
out-of-focus edges.
Edge contrast is high due to
sharp, in-focus edges.
Gray
scale
Tool position
Gray
scale
Tool position
When enlarged...
A position the system recognizes as an edge
may shift for one pixel at most. This will
prevent the execution of high-resolution
measurement.
M
Mz
My
Mx
Vx
Vy
V
Machine coordinate system Vision coordinate system
CCD
Z
coordinate
In-focus
height
Contrast
High High
Low Low
Contrast in the scanning direction Contrast in the scanning direction
Gray
scale
Gray
scale
Tool position
Tool position
Image signal without
sub-pixel processing
Image signal with sub-pixel processing
The image signal proﬁle
approaches an analog
waveform like this.

38
Surftest (Surface Roughness Testers)
■ JIS B 0601: 2001 Geometric Product Specifications (GPS) –Surface Texture: Profile method–
Feed device
Column
Probe (pickup)
Probe
Stylus
Workpiece
Fixture
Base
Measuring loop
Transducer
Measure-
ment
profile
Stylus tip
Reference
line
Reference
guide skid
Nominal
texture
suppression
Primary
profile
AD
converter
Profile
filter
Parameter
evaluation
according to
JIS B 0601
Amplifier
Feed
device
Workpiece
surface
Measure-
ment
loop
Appea-
rance
Drive Unit
Z-axis Signal Transfer Unit
Input/Output Input/Output
Quantized
measure-
ment
profile
Quantized
measure-
ment
profile
A profile filter is a phase-correct filter without phase delay (cause of profile
distortion dependent on wavelength).
The weight function of a phase-correct filter shows a normal (Gaussian)
distribution in which the amplitude transmission is 50% at the cutoff
wavelength.
■Nominal Characteristics of Contact (Stylus) Instruments
■Data Processing Flow
■Surface Profiles
■Metrological Characterization
of Phase Correct Filters
Surface profile
on the real surface
Measured
profile
Quantized
profile
Primary profile Primary profile
parameters
Roughness profile Waviness profile
Roughness
profile parameters
Waviness
profile parameters
Low-pass filter
of cutoff value λs
High-pass filter
of cutoff value λc
Band-pass filter that passes wavelengths
between cutoff values λc and λf
Measurement
AD conversion
Suppresses irrelevant geometry of the surface such as
inclination of a flat feature and curvature of a cylindrical
feature using the least squares method.
Definition: Profile that results from the
intersection of the real surface and
a plane rectangular to it.
Definition: Locus of the center of the stylus tip
that traces the workpiece surface.
Definition: Data obtained by quantizing
the measured profile.
JIS B 0651: 2001 (ISO 3274: 1996)
JIS B 0632: 2001
(ISO 11562: 1996)
60° 60° 60°
90° 90° 90°
R
2
µ
m
R
5
µ
m
R
1
0
µ
m
R
2
µ
m
R
5
µ
m
R
1
0
µ
m
Stylus Shape
A typical shape for a stylus end is conical with a spherical tip.
Tip radius: rtip = 2 µm, 5 µm or 10 µm
Taper angle of cone: 60°, 90°
In typical surface roughness testers, the taper angle of the stylus end is 60˚ unless
otherwise specified.
Static Measuring Force
Measuring force at the mean position of a stylus: 0.75mN
Ratio of measuring force variations: 0N/m
Standard characteristic value: Static measuring force at the mean position of
a stylus
Note 1: The maximum value of static measuring force at the average position of a stylus is to be
4.0mN for a special structured probe including a replaceable stylus.
Nominal radius of
curvature of stylus tip:
µm
Static measuring force at
the mean position of
stylus: mN
Toleranced ratio of static
measuring force
variations: mN/µm
2
5
10
0.75
0.75 (4.0)Note 1
0.035
0.2
Maximum sampling length
mm
λc
mm
λs
µm
λc/λs
Relationship between Cutoff Value and
Stylus Tip Radius
The following table lists the relationship between the roughness profile cutoff
value λc, stylus tip radius rtip, and cutoff ratio λc/λs.
Note 1: For a surface with Ra>0.5µm or Rz>3µm, a significant error will not usually
occur in a measurement even if rtip= 5µm.
Note 2: If a cutoff value ls is 2.5µm or 8µm, attenuation of the signal due to the mechanical filtering effect
of a stylus with the recommended tip radius appears outside the roughness profile pass band. Therefore,
a small error in stylus tip radius or shape does not affect parameter values calculated from measurements.
If a specific cutoff ratio is required, the ratio must be defined.
Maximum rtip
µm
Note 1
Note 2
Note 2
0.08
0.25
0.8
2.5
8
2.5
2.5
2.5
8
25
0.5
0.5
0.5
1.5
5
30
100
300
300
300
2
2
2
5
10
JIS B 0601: 2001 (ISO 4287: 1997)
50
100
λs λc λf
Amplitude
transmission
%
Wavelength
Roughness profile Waviness profile
Primary Profile
Profile obtained from the measured profile by applying a low-pass filter
with cutoff value λs.
Roughness Profile
Profile obtained from the primary profile by suppressing the longer
wavelength components using a high-pass filter of cutoff value λc.
Waviness Profile
Profile obtained by applying a band-pass filter to the primary profile to
remove the longer wavelengths above λf and the shorter
wavelengths below λc.
■Definition of Parameters
Rp
Sampling length
Amplitude Parameters (peak and valley)
Maximum peak height of the primary profile Pp
Maximum peak height of the roughness profile Rp
Maximum peak height of the waviness profile Wp
Largest profile peak height Zp within a sampling length
JIS B 0601 : 2001
(ISO 4287 : 1997)
Sampling length
Rv
Maximum valley depth of the primary profile Pv
Maximum valley depth of the roughness profile Rv
Maximum valley depth of the waviness profile Wv
Largest profile valley depth Zv within a sampling length
Rp
Sampling length
Rz
Rv
Maximum height of the primary profile Pz
Maximum height of the roughness profile Rz
Maximum height of the waviness profile Wz
Sum of height of the largest profile peak height Zp and the
largest profile valley depth Zv within a sampling length
In Old JIS and ISO 4287-1: 1984, Rz was used to indicate the
“ten point height of irregularities”. Care must be taken because
differences between results obtained according to the existing and
old standards are not always negligibly small. (Be sure to check whether the
drawing instructions conform to existing or old standards.)
Mean height of the primary profile elements Pc
Mean height of the roughness profile elements Rc
Mean height of the waviness profile elements Wc
Mean value of the profile element heights Zt within a sampling
length
m
m
Pc, Rc, Wc = Zti
i=1
1
Sampling length
Zt1
Zt2
Zt3
Zt4
Zt5
Zt6
Total height of the primary profile Pt
Total height of the roughness profile Rt
Total height of the waviness profile Wt
Sum of the height of the largest profile peak height Zp and the
largest profile valley depth Zv within the evaluation length
Evaluation length
Sampling
length
Rt
Rz
Rz
Rz
Σ
Primary profile
Primary profile

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